I came across this information today (wanted to see if one can eat Cherimoya skin, because i love it). The articles in the medical journals are too specific for me to understand, maybe you are interested and want to take a closer look?

http://forums2.gardenweb.com/forums/load/fruit/msg0317454513015.html

Please don't tell me to stop eating Cherimoyas. They are my staple in the winter and i love them dearly. :)